1. Field of the Invention
The present invention generally relates to an inkjet head and an inkjet plotter.
2. Description of the Related Art
There is an exemplary technique applied with MicroElectroMechanical System (MEMS) for densely packing an inkjet head using a piezoelectric element.
The inkjet head is obtained by patterning an individual electrode, an common electrode and a piezoelectric substance on a vibrating plate to thereby form a piezoelectric element as an actuator.
However, a piezoelectric substance may be degraded by moisture in the air.
Patent Document 1 discloses a flow path forming substrate on which a pressure generating chamber communicating with nozzle openings for discharging droplets, a piezoelectric element made of a lower electrode provided on one side surface of the flow path forming substrate via a vibrating plate, a piezoelectric substance layer and an upper electrode, and an upper electrode lead electrode drawn out of the upper electrode. At this time, pattern areas in the layers forming the piezoelectric element and the upper electrode lead electrode except for areas facing connection wirings of the lower electrode and the upper electrode lead electrode are coated by an insulating film made of an inorganic amorphous material. The insulating film includes a first insulating film and a second insulating film, and the piezoelectric element except for a connecting portion connected with the upper electrode lead electrode is covered by the first insulating film. The upper electrode lead electrode extends on the first insulating film. The pattern areas of the layers forming the piezoelectric element and the upper electrode lead electrode except for the area facing the connecting portion of the connection wirings is coated by the second insulating layer.
However, because the upper electrode lead electrode is not formed on the lower electrode, there is a problem that the inkjet head cannot be downsized.
Patent Document 1: Japanese Laid-Open Patent Application No. 2010-42683